Sequential double-labeling with 14C-2DG for one stimulational condition and 3H-2DG for a second allows direct comparison of patterns of activity within the same brain sections. We developed methods for separation of the 3H and 14C images directly on film. We hypothesized the existence of a lag between change in stimulus and corresponding change in 2DG uptake. At the termination of exercise, the increased metabolic activity in muscle does not cease instantly. Increased metabolic activity continues for some time, a period of "cool-down". Conversely, when we begin to exercise, there is a "warm-up" period before glucose utilization reaches its (high) steady-state level. To demonstrate this phenomena in brain, we took advantage of the ocular-dominance system in macaque striate cortex. One eye was occluded for 30 minutes; then an occluder was placed in the other eye as well, and an injection of 2DG was given at the same time. Thus, during the period of exposure to 2DG, the animal received no visual stimulation. Nonetheless, the autoradiograms of striate cortex show striking ocular dominance patterns, including stripes in layer IV and activation of half of the stripes of "puff" in layers II and III. Thus, the lag was confirmed, at least for cool-down.